Dame Thora Hird's agent Felix says she's too busy and the last thing she needs is publicity. We tell him we're so desperate we'll hold the interview slot open until she can squeeze us in. Humph, that won't wash with Dame Thora, he says: "How much do you pay? Thora believes if they give you nowt you're worth nowt." Sorry, it's the Guardian, we don't pay - tightness masquerading as moral superiority. Well, maybe Saturday. But if you try any of that aggressive nonsense with Thora, you'll be out on your ear.

Saturday morning, and I'm climbing the daunting stairs of her mews house in west London. It's a strange building - more confectionery than house. Thora's watching the rugby. She's sat in her comfy chair, looking ever so glam. Black velvet suit, black and white shirt, a smudge of red lipstick, hair still a dull blonde. "It's a man's game, isn't it love? Not like football these days - all the footballers just want to be film-stars. Would you like coffee, Simon? Nola!"

The 1990s began bleakly for Thora. First the BBC scrapped Praise Be!, the religious programme she had presented for 17 years. Then, four years ago, her husband, Jimmy Scott, died. And last year she had a horribly farcical accident involving split peas that resulted in two broken arteries in a foot. So Thora set to work. She hired Nola as a full time helper/carer/friend, had a lift installed, fought her way back to health and conjured up some of her greatest performances.

At 87, she has won three awards this year, including television actress of the year for Alan Bennett's Waiting For The Telegram. As centenarian Violet she is heartbreaking and erotic, still in touch with desire, looking back to the day before her boyfriend went to be killed in the first world war.

She introduces me to Scotty by way of a photograph on her sideboard. "That is the best picture of my husband and my grandson. He was a good man." The picture is taken in Beverly Hills where her daughter, the former child movie star Janette Scott, used to live. "We had 54 years together. It was a wonderful life. And you see, Simon, I was ashamed that I didn't know it was a stroke he'd had. I was getting ready to go to work in the back, and we've got two bedrooms, and I was in one and he was in the other, not because we didn't speak to each other, because my arthritis, well, with all this you wouldn't ask the cat to sleep with me. And I was doing my hair, getting ready to go to rehearsal, when I heard this thud which I thought was my copper pans on the wall which you'll see before you go, cleanest in London. And I said, 'Was that one of the pans on the floor?' and nobody answers, so I came out and saw a light under the bathroom door, and he'd fallen into the bath. There was no water in it, and he was dressed, and - it's a terrible thing to say, only God understands me very, very well - the first thing I thought was, 'Why are your shoes cleaner than anyone else's?'" She can't help making the story as funny as it is tragic.

He was in a coma for three weeks. Thora knew it was hopeless. "I sat on the edge of my bed and I had a word or two with the Lord and said would you take him in his sleep. This is 7.30 in the evening. Well, two o'clock that morning he died. And when I came back I sat on my bed again and had another word with the Lord, 'cos this man and I were in love. We came back from our honeymoon with three and eightpence old money in the world, in the world, and he said, 'You will get on, you will, and when you do we'll go round the world', and we laughed for an hour. And we did. We did go round the world."

You don't interview Thora, you listen in awe. Each story is a self-contained play. The detail is astonishing, the tangents surreal. She sits there, rigid in her chair, laughter lines dancing across her face, and talks and talks and talks in concentrated Lancashire. Her tongue lollops from one side of her mouth to the other, moistening her lips, keeping them fit for work.

She likes to call Scotty "the first house-husband". He had been a musician, "a good 'un, too", but he gave it all up for her. "He said: 'Well, I'll never make the money you will, and one of us has to stay at home, because we've got this lovely baby'."

She apologises for wheeling away at another tangent, but she must tell me how she got pregnant. "When we'd been married a year he bought me a bunch of white chrysanths, and he said, 'I wish I'd bought you something you could have kept,' and I said, 'You can, we'll make a baby tonight,' and we did. I went to the doctor's, and she smoked State Express 333, and I tell you that because I smoked Players in those days, and she said, 'What's the matter, have you got kidney failure?' And I said, 'No, I'm pregnant.'

"She said get on that couch and I get my skirt suit off, and she says: 'How far are you gone?' And I say three days and she says 'Get off that bloody couch!' So I said, 'Right, I'll tell you what - I'll bet you 100 State Express 333 that I am preggers.' And she said, 'Right I'll bet you 100 what is it you smoke?' And I got those Players all right. I said to her, 'You're a fool to yourself, he knows what it's for and he's used it in the right way.' Nola! I don't know where the hell she is."

I offer to get the coffee. "No. No! She works for me. Ah, could you bring the Thermos in, please, love?" Thora made her debut in the local Morecambe theatre at eight weeks old. Mum was an actress, dad a director, and she was hired as a prop. "I can honestly say it was the only job I got through my influence." She often returns to the memory of her parents. Her mother, who would do anything for anyone her father, who taught her how to play for laughs and silence, yet found it so difficult to praise her.

She tells me about the time she knew she'd got it just right. "And Dad starts analysing the cast: 'The boy was good who played so-and-so, and the girl was good..." And he gets to the door to go out, and I said: 'How did you think I was, Dad?' And he just put his face round, and said: 'You're a wonderful bloody actress.' I said: 'What?' He said: 'I've lived to see how you acted tonight.' And he was dead next morning." Thora is weeping gently. "Suppose he'd never said anything to me, Simon? D'you want a gin and tonic?"

She says she couldn't have had the career she did without Scotty's cleaning and cooking, "not that there was anything poofter about him", and moves seamlessly on to the many poofters who do for her. "I've got a lot of poof friends now. And they are lovely and kind, and some of them are dog-collars." Thora calls me to look at a photo album. "I've never shown anyone these before, Simon." There are sharp, sensual photographs of primroses taken by her daughter, and pictures of her grandchildren. She holds my arm and says her daughter has given her more happiness than anything she has achieved professionally.

Why does she continue to work? She says she loves it, it keeps her mind fresh, and she needs the money. "I have four sets of wages to pay. There's Nola, who's expensive but good. Lydia, my cleaner - she'd shoot anyone who hurt me, she'd hit 'em, anyway. I have a secretary for my business, and a secretary for my books. I'm blessed, you see. Nola! Would you pour Simon a Scotch? I'll just have a little sherry if you don't mind. Isn't it awful, I've not stopped talking. Are you having one, Nola?"

Thora was recently sent a script that she had to turn down because of the four-letter words. I say she didn't seem to have much problem talking about the flasher's penis in the Bennett play. "Well, I'll tell you something. I wrote a song about it once, but I won't tell it you while that thing's on," she says, pointing to the tape recorder. She can't resist, though.

"My husband was a bedpan-wallah in the war, and at the hospital they had a Christmas party and he said three of them were dressing up as nurses, and he was no poof, don't worry, and he says will you write me a trio for the three of us in nurses' uniform. So I sat down and thought..."

Thora begins to sing. "We are three little medics here, Penis, Scrotum and Anus, /If it wasn't for us you wouldn't be here, /Penis, Scrotum, and Anus./ I give you pleasure I give you joy,/I sometimes grab you a girl or a boy,/Penis, Scrotum and Anus. Then the second verse goes: And though we are so very refined/Penis, Scrotum and Anus/ Penis said I'm in front, and Anus said I'm behind. Heeheehee!,/Penis Scrotum and Anus. And then Scrotum says: Though sometimes the glamour palls,/I'm joked about in the music halls, And I'm often referred to as orchestra stalls. And I said to Scotty you won't tell anyone I've written it and he said, 'Well, of course I bloody won't'."

Song over, Thora returns to the stories. The 24 times she's met the Queen, her nine times with Diana ("the Queen of titters"), the new campaign with Help The Aged to keep old people warm, how she learnt her posh voice from Auntie Nelly in Manchester who was four feet nine and planted three sausages on her hair to make her look taller. It's time to leave, but only because the tapes have run out. We'll meet again, says Thora. "Bye bye love. God bless." And, confirmed atheist though I am, I hear myself whispering God bless.